Anthrax vs. Cancer – Researchers Harness Deadly Toxin to Cure Dogs and Potentially People

Dogs with terminal bladder cancer improved with a new modified anthrax treatment. pyotr021 / iStock / Getty Images Plus
By R. Claudio Aguilar
Can the feared anthrax toxin become an ally in the war against cancer? Successful treatment of pet dogs suffering bladder cancer with an anthrax-related treatment suggests so.
Anthrax is a disease caused a by bacterium, known as Bacillus anthracis, which releases a toxin that causes the skin to break down and forms ulcers, and triggers pneumonia and muscle and chest pain. To add to its sinister resumé, and underscore its lethal effects, this toxin has been infamously used as a bioweapon.
However, my colleagues and I found a way to tame this killer and put it to good use against another menace: bladder cancer.
I am a biochemist and cell biologist who has been working on research and development of novel therapeutic approaches against cancer and genetic diseases for more than 20 years. Our lab has investigated, designed and adapted agents to fight disease; this is our latest exciting story.
Pressing Needs
Among all cancers, the one affecting the bladder is the sixth most common and in 2019 caused more than 17,000 deaths in the U.S. Of all patients that receive surgery to remove this cancer, about 70% will return to the physician's office with more tumors. This is psychologically devastating for the patient and makes the cancer of the bladder one of the most expensive to treat.
To make things worse, currently there is a worldwide shortage of Bacillus Calmette-Guerin, a bacterium used to make the preferred immunotherapy for decreasing bladder cancer recurrence after surgery. This situation has left doctors struggling to meet the needs of their patients. Therefore, there is a clear need for more effective strategies to treat bladder cancer.
Anthrax Comes to the Rescue
Years ago scientists in the Collier lab modified the anthrax toxin by physically linking it to a naturally occurring protein called the epidermal growth factor (EGF) that binds to the EGF receptor, which is abundant on the surface of bladder cancer cells. When the EGF protein binds to the receptor – like a key fits a lock – it causes the cell to engulf the EGF-anthrax toxin, which then induces the cancer cell to commit suicide (a process called apoptosis), while leaving healthy cells alone.
In collaboration with colleagues at Indiana University medical school, Harvard University and MIT, we designed a strategy to eliminate tumors using this modified toxin. Together we demonstrated that this novel approach allowed us to eliminate tumor cells taken from human, dog and mouse bladder cancer.
This highlights the potential of this agent to provide an efficient and fast alternative to the current treatments (which can take between two and three hours to administer over a period of months). I also think it is good news is that the modified anthrax toxin spared normal cells. This suggests that this treatment could have fewer side effects.
Helping Our Best Friends
These encouraging results led my lab to join forces with Dr. Knapp's group at the Purdue veterinary hospital to treat pet dogs suffering from bladder cancer.
Canine patients for whom all available conventional anti-cancer therapeutics were unsuccessful were considered eligible for these tests. Only after standard tests proved the agent to be safe in laboratory animals, and with the consent of their owners, six eligible dogs with terminal bladder cancer were treated with the anthrax toxin-derived agent.
Two to five doses of this medicine, delivered directly inside the bladder via a catheter, was enough to shrink the tumor by an average of 30%. We consider these results impressive given the initial large size of the tumor and its resistance to other treatments.
There Is Hope for All
Our collaborators at Indiana University Hospital surgically removed bladder cells from human patients and sent them to my lab for testing the agent. At Purdue my team found these cells to be very sensitive to the anthrax toxin-derived agent as well. These results suggest that this novel anti-bladder cancer strategy could be effective in human patients.
The treatment strategy that we have devised is still experimental. Therefore, it is not available for treatment of human patients yet. Nevertheless, my team is actively seeking the needed economic support and required approvals to move this therapeutic approach into human clinical trials. Plans to develop a new, even better generation of agents and to expand their application to the fight against other cancers are ongoing.
R. Claudio Aguilar is an associate professor of biological sciences at Purdue University.
Disclosure statement: R. Claudio Aguilar received funding from National Institutes of Health.
Reposted with permission from The Conversation.
- Redwoods are the world's tallest trees.
- Now scientists have discovered they are even bigger than we thought.
- Using laser technology they map the 80-meter giants.
- Trees are a key plank in the fight against climate change.
They are among the largest trees in the world, descendants of forests where dinosaurs roamed.
Pixabay / Simi Luft
<p><span>Until recently, measuring these trees meant scaling their 80 meter high trunks with a tape measure. Now, a team of scientists from University College London and the University of Maryland uses advanced laser scanning, to create 3D maps and calculate the total mass.</span></p><p>The results are striking: suggesting the trees <a href="https://www.nature.com/articles/s41598-020-73733-6" target="_blank" rel="noopener noreferrer">may be as much as 30% larger than earlier measurements suggested.</a> Part of that could be due to the additional trunks the Redwoods can grow as they age, <a href="https://www.nature.com/articles/s41598-020-73733-6" target="_blank" rel="noopener noreferrer">a process known as reiteration</a>.</p>New 3D measurements of large redwood trees for biomass and structure. Nature / UCL
<p>Measuring the trees more accurately is important because carbon capture will probably play a key role in the battle against climate change. Forest <a href="https://www.wri.org/blog/2020/09/carbon-sequestration-natural-forest-regrowth" target="_blank">growth could absorb billions of tons</a> of carbon dioxide from the atmosphere each year.</p><p>"The importance of big trees is widely-recognised in terms of carbon storage, demographics and impact on their surrounding ecosystems," the authors wrote<a href="https://www.nature.com/articles/s41598-020-73733-6" target="_blank"> in the journal Nature</a>. "Unfortunately the importance of big trees is in direct proportion to the difficulty of measuring them."</p><p>Redwoods are so long lived because of their ability to <a href="https://www.nature.com/articles/s41598-020-73733-6" target="_blank" rel="noopener noreferrer">cope with climate change, resist disease and even survive fire damage</a>, the scientists say. Almost a fifth of their volume may be bark, which helps protect them.</p>Carbon Capture Champions
<p><span>Earlier research by scientists at Humboldt University and the University of Washington found that </span><a href="https://www.sciencedirect.com/science/article/pii/S0378112716302584" target="_blank" rel="noopener noreferrer">Redwood forests store almost 2,600 tonnes of carbon per hectare</a><span>, their bark alone containing more carbon than any other neighboring species.</span></p><p>While the importance of trees in fighting climate change is widely accepted, not all species enjoy the same protection as California's coastal Redwoods. In 2019 the world lost the equivalent of <a href="https://www.worldwildlife.org/threats/deforestation-and-forest-degradation" target="_blank" rel="noopener noreferrer">30 soccer fields of forest cover every minute</a>, due to agricultural expansion, logging and fires, according to The Worldwide Fund for Nature (WWF).</p>Pixabay
<p>Although <a href="https://c402277.ssl.cf1.rackcdn.com/publications/1420/files/original/Deforestation_fronts_-_drivers_and_responses_in_a_changing_world_-_full_report_%281%29.pdf?1610810475" target="_blank" rel="noopener noreferrer">the rate of loss is reported to have slowed in recent years</a>, reforesting the world to help stem climate change is a massive task.</p><p><span>That's why the World Economic Forum launched the Trillion Trees Challenge (</span><a href="https://www.1t.org/" target="_blank" rel="noopener noreferrer">1t.org</a><span>) and is engaging organizations and individuals across the globe through its </span><a href="https://uplink.weforum.org/uplink/s/uplink-issue/a002o00000vOf09AAC/trillion-trees" target="_blank" rel="noopener noreferrer">Uplink innovation crowdsourcing platform</a><span> to support the project.</span></p><p>That's backed up by research led by ETH Zurich/Crowther Lab showing there's potential to restore tree coverage across 2.2 billion acres of degraded land.</p><p>"Forests are critical to the health of the planet," according to <a href="https://www.1t.org/" target="_blank" rel="noopener noreferrer">1t.org</a>. "They sequester carbon, regulate global temperatures and freshwater flows, recharge groundwater, anchor fertile soil and act as flood barriers."</p><p><em data-redactor-tag="em" data-verified="redactor">Reposted with permission from the </em><span><em data-redactor-tag="em" data-verified="redactor"><a href="https://www.weforum.org/agenda/2021/03/redwoods-store-more-co2-and-are-more-enormous-than-we-thought/" target="_blank">World Economic Forum</a>.</em></span></p>EcoWatch Daily Newsletter
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